From 4bfcd159944e7387f701cceb85b26f6d6d17fbed Mon Sep 17 00:00:00 2001
From: James Hughes <james.hughes@raspberrypi.org>
Date: Thu, 14 Mar 2019 13:27:54 +0000
Subject: [PATCH] Pulled in the multi frame buffer support from the Pi3
 repo

---
 drivers/video/fbdev/bcm2708_fb.c | 457 ++++++++++++++++++++++---------
 1 file changed, 324 insertions(+), 133 deletions(-)

--- a/drivers/video/fbdev/bcm2708_fb.c
+++ b/drivers/video/fbdev/bcm2708_fb.c
@@ -2,6 +2,7 @@
  *  linux/drivers/video/bcm2708_fb.c
  *
  * Copyright (C) 2010 Broadcom
+ * Copyright (C) 2018 Raspberry Pi (Trading) Ltd
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file COPYING in the main directory of this archive
@@ -13,6 +14,7 @@
  * Copyright 1999-2001 Jeff Garzik <jgarzik@pobox.com>
  *
  */
+
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -33,6 +35,7 @@
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
 #include <soc/bcm2835/raspberrypi-firmware.h>
+#include <linux/mutex.h>
 
 //#define BCM2708_FB_DEBUG
 #define MODULE_NAME "bcm2708_fb"
@@ -79,64 +82,150 @@ struct bcm2708_fb_stats {
 	u32 dma_irqs;
 };
 
+struct vc4_display_settings_t {
+	u32 display_num;
+	u32 width;
+	u32 height;
+	u32 depth;
+	u32 pitch;
+	u32 virtual_width;
+	u32 virtual_height;
+	u32 virtual_width_offset;
+	u32 virtual_height_offset;
+	unsigned long fb_bus_address;
+};
+
+struct bcm2708_fb_dev;
+
 struct bcm2708_fb {
 	struct fb_info fb;
 	struct platform_device *dev;
-	struct rpi_firmware *fw;
 	u32 cmap[16];
 	u32 gpu_cmap[256];
-	int dma_chan;
-	int dma_irq;
-	void __iomem *dma_chan_base;
-	void *cb_base;		/* DMA control blocks */
-	dma_addr_t cb_handle;
 	struct dentry *debugfs_dir;
-	wait_queue_head_t dma_waitq;
-	struct bcm2708_fb_stats stats;
+	struct dentry *debugfs_subdir;
 	unsigned long fb_bus_address;
-	bool disable_arm_alloc;
+	struct { u32 base, length; } gpu;
+	struct vc4_display_settings_t display_settings;
+	struct debugfs_regset32 screeninfo_regset;
+	struct bcm2708_fb_dev *fbdev;
 	unsigned int image_size;
 	dma_addr_t dma_addr;
 	void *cpuaddr;
 };
 
+#define MAX_FRAMEBUFFERS 3
+
+struct bcm2708_fb_dev {
+	int firmware_supports_multifb;
+	/* Protects the DMA system from multiple FB access */
+	struct mutex dma_mutex;
+	int dma_chan;
+	int dma_irq;
+	void __iomem *dma_chan_base;
+	wait_queue_head_t dma_waitq;
+	bool disable_arm_alloc;
+	struct bcm2708_fb_stats dma_stats;
+	void *cb_base;	/* DMA control blocks */
+	dma_addr_t cb_handle;
+	int instance_count;
+	int num_displays;
+	struct rpi_firmware *fw;
+	struct bcm2708_fb displays[MAX_FRAMEBUFFERS];
+};
+
 #define to_bcm2708(info)	container_of(info, struct bcm2708_fb, fb)
 
 static void bcm2708_fb_debugfs_deinit(struct bcm2708_fb *fb)
 {
-	debugfs_remove_recursive(fb->debugfs_dir);
-	fb->debugfs_dir = NULL;
+	debugfs_remove_recursive(fb->debugfs_subdir);
+	fb->debugfs_subdir = NULL;
+
+	fb->fbdev->instance_count--;
+
+	if (!fb->fbdev->instance_count) {
+		debugfs_remove_recursive(fb->debugfs_dir);
+		fb->debugfs_dir = NULL;
+	}
 }
 
 static int bcm2708_fb_debugfs_init(struct bcm2708_fb *fb)
 {
+	char buf[3];
+	struct bcm2708_fb_dev *fbdev = fb->fbdev;
+
 	static struct debugfs_reg32 stats_registers[] = {
-		{
-			"dma_copies",
-			offsetof(struct bcm2708_fb_stats, dma_copies)
-		},
-		{
-			"dma_irqs",
-			offsetof(struct bcm2708_fb_stats, dma_irqs)
-		},
+	{"dma_copies", offsetof(struct bcm2708_fb_stats, dma_copies)},
+	{"dma_irqs",   offsetof(struct bcm2708_fb_stats, dma_irqs)},
 	};
 
-	fb->debugfs_dir = debugfs_create_dir(DRIVER_NAME, NULL);
+	static struct debugfs_reg32 screeninfo[] = {
+	{"width",	 offsetof(struct fb_var_screeninfo, xres)},
+	{"height",	 offsetof(struct fb_var_screeninfo, yres)},
+	{"bpp",		 offsetof(struct fb_var_screeninfo, bits_per_pixel)},
+	{"xres_virtual", offsetof(struct fb_var_screeninfo, xres_virtual)},
+	{"yres_virtual", offsetof(struct fb_var_screeninfo, yres_virtual)},
+	{"xoffset",	 offsetof(struct fb_var_screeninfo, xoffset)},
+	{"yoffset",	 offsetof(struct fb_var_screeninfo, yoffset)},
+	};
+
+	fb->debugfs_dir = debugfs_lookup(DRIVER_NAME, NULL);
+
+	if (!fb->debugfs_dir)
+		fb->debugfs_dir = debugfs_create_dir(DRIVER_NAME, NULL);
+
 	if (!fb->debugfs_dir) {
-		pr_warn("%s: could not create debugfs entry\n",
-			__func__);
+		dev_warn(fb->fb.dev, "%s: could not create debugfs folder\n",
+			 __func__);
 		return -EFAULT;
 	}
 
-	fb->stats.regset.regs = stats_registers;
-	fb->stats.regset.nregs = ARRAY_SIZE(stats_registers);
-	fb->stats.regset.base = &fb->stats;
+	snprintf(buf, sizeof(buf), "%u", fb->display_settings.display_num);
+
+	fb->debugfs_subdir = debugfs_create_dir(buf, fb->debugfs_dir);
 
 	debugfs_create_regset32("stats", 0444, fb->debugfs_dir,
 				&fb->stats.regset);
+
+	if (!fb->debugfs_subdir) {
+		dev_warn(fb->fb.dev, "%s: could not create debugfs entry %u\n",
+			 __func__, fb->display_settings.display_num);
+		return -EFAULT;
+	}
+
+	fbdev->dma_stats.regset.regs = stats_registers;
+	fbdev->dma_stats.regset.nregs = ARRAY_SIZE(stats_registers);
+	fbdev->dma_stats.regset.base = &fbdev->dma_stats;
+
+	debugfs_create_regset32("dma_stats", 0444, fb->debugfs_subdir,
+				&fbdev->dma_stats.regset);
+
+	fb->screeninfo_regset.regs = screeninfo;
+	fb->screeninfo_regset.nregs = ARRAY_SIZE(screeninfo);
+	fb->screeninfo_regset.base = &fb->fb.var;
+
+	debugfs_create_regset32("screeninfo", 0444, fb->debugfs_subdir,
+				&fb->screeninfo_regset);
+
+	fbdev->instance_count++;
+
 	return 0;
 }
 
+static void set_display_num(struct bcm2708_fb *fb)
+{
+	if (fb && fb->fbdev && fb->fbdev->firmware_supports_multifb) {
+		u32 tmp = fb->display_settings.display_num;
+
+		if (rpi_firmware_property(fb->fbdev->fw,
+					  RPI_FIRMWARE_FRAMEBUFFER_SET_DISPLAY_NUM,
+					  &tmp,
+					  sizeof(tmp)))
+			dev_warn_once(fb->fb.dev,
+				      "Set display number call failed. Old GPU firmware?");
+	}
+}
+
 static int bcm2708_fb_set_bitfields(struct fb_var_screeninfo *var)
 {
 	int ret = 0;
@@ -214,11 +303,11 @@ static int bcm2708_fb_check_var(struct f
 				struct fb_info *info)
 {
 	/* info input, var output */
-	print_debug("%s(%p) %dx%d (%dx%d), %d, %d\n",
+	print_debug("%s(%p) %ux%u (%ux%u), %ul, %u\n",
 		    __func__, info, info->var.xres, info->var.yres,
 		    info->var.xres_virtual, info->var.yres_virtual,
-		    (int)info->screen_size, info->var.bits_per_pixel);
-	print_debug("%s(%p) %dx%d (%dx%d), %d\n", __func__, var, var->xres,
+		    info->screen_size, info->var.bits_per_pixel);
+	print_debug("%s(%p) %ux%u (%ux%u), %u\n", __func__, var, var->xres,
 		    var->yres, var->xres_virtual, var->yres_virtual,
 		    var->bits_per_pixel);
 
@@ -281,17 +370,24 @@ static int bcm2708_fb_set_par(struct fb_
 	};
 	int ret, image_size;
 
-
-	print_debug("%s(%p) %dx%d (%dx%d), %d, %d\n", __func__, info,
+	print_debug("%s(%p) %dx%d (%dx%d), %d, %d (display %d)\n", __func__,
+		    info,
 		    info->var.xres, info->var.yres, info->var.xres_virtual,
 		    info->var.yres_virtual, (int)info->screen_size,
-		    info->var.bits_per_pixel);
+		    info->var.bits_per_pixel, value);
+
+	/* Need to set the display number to act on first
+	 * Cannot do it in the tag list because on older firmware the call
+	 * will fail and stop the rest of the list being executed.
+	 * We can ignore this call failing as the default at other end is 0
+	 */
+	set_display_num(fb);
 
 	/* Try allocating our own buffer. We can specify all the parameters */
 	image_size = ((info->var.xres * info->var.yres) *
 		      info->var.bits_per_pixel) >> 3;
 
-	if (!fb->disable_arm_alloc &&
+	if (!fb->fbdev->disable_arm_alloc &&
 	    (image_size != fb->image_size || !fb->dma_addr)) {
 		if (fb->dma_addr) {
 			dma_free_coherent(info->device, fb->image_size,
@@ -306,7 +402,7 @@ static int bcm2708_fb_set_par(struct fb_
 
 		if (!fb->cpuaddr) {
 			fb->dma_addr = 0;
-			fb->disable_arm_alloc = true;
+			fb->fbdev->disable_arm_alloc = true;
 		} else {
 			fb->image_size = image_size;
 		}
@@ -317,7 +413,7 @@ static int bcm2708_fb_set_par(struct fb_
 		fbinfo.screen_size = image_size;
 		fbinfo.pitch = (info->var.xres * info->var.bits_per_pixel) >> 3;
 
-		ret = rpi_firmware_property_list(fb->fw, &fbinfo,
+		ret = rpi_firmware_property_list(fb->fbdev->fw, &fbinfo,
 						 sizeof(fbinfo));
 		if (ret || fbinfo.base != fb->dma_addr) {
 			/* Firmware either failed, or assigned a different base
@@ -330,7 +426,7 @@ static int bcm2708_fb_set_par(struct fb_
 			fb->image_size = 0;
 			fb->cpuaddr = NULL;
 			fb->dma_addr = 0;
-			fb->disable_arm_alloc = true;
+			fb->fbdev->disable_arm_alloc = true;
 		}
 	} else {
 		/* Our allocation failed - drop into the old scheme of
@@ -349,7 +445,7 @@ static int bcm2708_fb_set_par(struct fb_
 		fbinfo.tag6.tag = RPI_FIRMWARE_FRAMEBUFFER_GET_PITCH;
 		fbinfo.pitch = 0;
 
-		ret = rpi_firmware_property_list(fb->fw, &fbinfo,
+		ret = rpi_firmware_property_list(fb->fbdev->fw, &fbinfo,
 						 sizeof(fbinfo));
 		if (ret) {
 			dev_err(info->device,
@@ -439,7 +535,10 @@ static int bcm2708_fb_setcolreg(unsigned
 			packet->length = regno + 1;
 			memcpy(packet->cmap, fb->gpu_cmap,
 			       sizeof(packet->cmap));
-			ret = rpi_firmware_property(fb->fw,
+
+			set_display_num(fb);
+
+			ret = rpi_firmware_property(fb->fbdev->fw,
 						    RPI_FIRMWARE_FRAMEBUFFER_SET_PALETTE,
 						    packet,
 						    (2 + packet->length) * sizeof(u32));
@@ -478,8 +577,11 @@ static int bcm2708_fb_blank(int blank_mo
 		return -EINVAL;
 	}
 
-	ret = rpi_firmware_property(fb->fw, RPI_FIRMWARE_FRAMEBUFFER_BLANK,
+	set_display_num(fb);
+
+	ret = rpi_firmware_property(fb->fbdev->fw, RPI_FIRMWARE_FRAMEBUFFER_BLANK,
 				    &value, sizeof(value));
+
 	if (ret)
 		dev_err(info->device, "%s(%d) failed: %d\n", __func__,
 			blank_mode, ret);
@@ -496,12 +598,14 @@ static int bcm2708_fb_pan_display(struct
 	info->var.yoffset = var->yoffset;
 	result = bcm2708_fb_set_par(info);
 	if (result != 0)
-		pr_err("%s(%d,%d) returns=%d\n", __func__, var->xoffset,
+		pr_err("%s(%u,%u) returns=%d\n", __func__, var->xoffset,
 		       var->yoffset, result);
 	return result;
 }
 
 static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
+static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd,
+			 unsigned long arg)
 {
 	struct bcm2708_fb *fb = to_bcm2708(info);
 	u32 dummy = 0;
@@ -509,7 +613,9 @@ static int bcm2708_ioctl(struct fb_info
 
 	switch (cmd) {
 	case FBIO_WAITFORVSYNC:
-		ret = rpi_firmware_property(fb->fw,
+		set_display_num(fb);
+
+		ret = rpi_firmware_property(fb->fbdev->fw,
 					    RPI_FIRMWARE_FRAMEBUFFER_SET_VSYNC,
 					    &dummy, sizeof(dummy));
 		break;
@@ -526,23 +632,22 @@ static int bcm2708_ioctl(struct fb_info
 static void bcm2708_fb_fillrect(struct fb_info *info,
 				const struct fb_fillrect *rect)
 {
-	/* (is called) print_debug("bcm2708_fb_fillrect\n"); */
 	cfb_fillrect(info, rect);
 }
 
 /* A helper function for configuring dma control block */
 static void set_dma_cb(struct bcm2708_dma_cb *cb,
-		       int        burst_size,
-		       dma_addr_t dst,
-		       int        dst_stride,
-		       dma_addr_t src,
-		       int        src_stride,
-		       int        w,
-		       int        h)
+		int        burst_size,
+		dma_addr_t dst,
+		int        dst_stride,
+		dma_addr_t src,
+		int        src_stride,
+		int        w,
+		int        h)
 {
 	cb->info = BCM2708_DMA_BURST(burst_size) | BCM2708_DMA_S_WIDTH |
-		   BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
-		   BCM2708_DMA_D_INC | BCM2708_DMA_TDMODE;
+		BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
+		BCM2708_DMA_D_INC | BCM2708_DMA_TDMODE;
 	cb->dst = dst;
 	cb->src = src;
 	/*
@@ -560,15 +665,19 @@ static void bcm2708_fb_copyarea(struct f
 				const struct fb_copyarea *region)
 {
 	struct bcm2708_fb *fb = to_bcm2708(info);
-	struct bcm2708_dma_cb *cb = fb->cb_base;
+	struct bcm2708_fb_dev *fbdev = fb->fbdev;
+	struct bcm2708_dma_cb *cb = fbdev->cb_base;
 	int bytes_per_pixel = (info->var.bits_per_pixel + 7) >> 3;
 
 	/* Channel 0 supports larger bursts and is a bit faster */
-	int burst_size = (fb->dma_chan == 0) ? 8 : 2;
+	int burst_size = (fbdev->dma_chan == 0) ? 8 : 2;
 	int pixels = region->width * region->height;
 
-	/* Fallback to cfb_copyarea() if we don't like something */
-	if (bytes_per_pixel > 4 ||
+	/* If DMA is currently in use (ie being used on another FB), then
+	 * rather than wait for it to finish, just use the cfb_copyarea
+	 */
+	if (!mutex_trylock(&fbdev->dma_mutex) ||
+	    bytes_per_pixel > 4 ||
 	    info->var.xres * info->var.yres > 1920 * 1200 ||
 	    region->width <= 0 || region->width > info->var.xres ||
 	    region->height <= 0 || region->height > info->var.yres ||
@@ -595,8 +704,8 @@ static void bcm2708_fb_copyarea(struct f
 		 * 1920x1200 resolution at 32bpp pixel depth.
 		 */
 		int y;
-		dma_addr_t control_block_pa = fb->cb_handle;
-		dma_addr_t scratchbuf = fb->cb_handle + 16 * 1024;
+		dma_addr_t control_block_pa = fbdev->cb_handle;
+		dma_addr_t scratchbuf = fbdev->cb_handle + 16 * 1024;
 		int scanline_size = bytes_per_pixel * region->width;
 		int scanlines_per_cb = (64 * 1024 - 16 * 1024) / scanline_size;
 
@@ -646,10 +755,10 @@ static void bcm2708_fb_copyarea(struct f
 		}
 		set_dma_cb(cb, burst_size,
 			   fb->fb_bus_address + dy * fb->fb.fix.line_length +
-						   bytes_per_pixel * region->dx,
+			   bytes_per_pixel * region->dx,
 			   stride,
 			   fb->fb_bus_address + sy * fb->fb.fix.line_length +
-						   bytes_per_pixel * region->sx,
+			   bytes_per_pixel * region->sx,
 			   stride,
 			   region->width * bytes_per_pixel,
 			   region->height);
@@ -659,32 +768,33 @@ static void bcm2708_fb_copyarea(struct f
 	cb->next = 0;
 
 	if (pixels < dma_busy_wait_threshold) {
-		bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
-		bcm_dma_wait_idle(fb->dma_chan_base);
+		bcm_dma_start(fbdev->dma_chan_base, fbdev->cb_handle);
+		bcm_dma_wait_idle(fbdev->dma_chan_base);
 	} else {
-		void __iomem *dma_chan = fb->dma_chan_base;
+		void __iomem *local_dma_chan = fbdev->dma_chan_base;
 
 		cb->info |= BCM2708_DMA_INT_EN;
-		bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
-		while (bcm_dma_is_busy(dma_chan)) {
-			wait_event_interruptible(fb->dma_waitq,
-						 !bcm_dma_is_busy(dma_chan));
+		bcm_dma_start(fbdev->dma_chan_base, fbdev->cb_handle);
+		while (bcm_dma_is_busy(local_dma_chan)) {
+			wait_event_interruptible(fbdev->dma_waitq,
+						 !bcm_dma_is_busy(local_dma_chan));
 		}
-		fb->stats.dma_irqs++;
+		fbdev->dma_stats.dma_irqs++;
 	}
-	fb->stats.dma_copies++;
+	fbdev->dma_stats.dma_copies++;
+
+	mutex_unlock(&fbdev->dma_mutex);
 }
 
 static void bcm2708_fb_imageblit(struct fb_info *info,
 				 const struct fb_image *image)
 {
-	/* (is called) print_debug("bcm2708_fb_imageblit\n"); */
 	cfb_imageblit(info, image);
 }
 
 static irqreturn_t bcm2708_fb_dma_irq(int irq, void *cxt)
 {
-	struct bcm2708_fb *fb = cxt;
+	struct bcm2708_fb_dev *fbdev = cxt;
 
 	/* FIXME: should read status register to check if this is
 	 * actually interrupting us or not, in case this interrupt
@@ -694,9 +804,9 @@ static irqreturn_t bcm2708_fb_dma_irq(in
 	 */
 
 	/* acknowledge the interrupt */
-	writel(BCM2708_DMA_INT, fb->dma_chan_base + BCM2708_DMA_CS);
+	writel(BCM2708_DMA_INT, fbdev->dma_chan_base + BCM2708_DMA_CS);
 
-	wake_up(&fb->dma_waitq);
+	wake_up(&fbdev->dma_waitq);
 	return IRQ_HANDLED;
 }
 
@@ -729,11 +839,23 @@ static int bcm2708_fb_register(struct bc
 	fb->fb.fix.ywrapstep = 0;
 	fb->fb.fix.accel = FB_ACCEL_NONE;
 
-	fb->fb.var.xres = fbwidth;
-	fb->fb.var.yres = fbheight;
-	fb->fb.var.xres_virtual = fbwidth;
-	fb->fb.var.yres_virtual = fbheight;
-	fb->fb.var.bits_per_pixel = fbdepth;
+	/* If we have data from the VC4 on FB's, use that, otherwise use the
+	 * module parameters
+	 */
+	if (fb->display_settings.width) {
+		fb->fb.var.xres = fb->display_settings.width;
+		fb->fb.var.yres = fb->display_settings.height;
+		fb->fb.var.xres_virtual = fb->fb.var.xres;
+		fb->fb.var.yres_virtual = fb->fb.var.yres;
+		fb->fb.var.bits_per_pixel = fb->display_settings.depth;
+	} else {
+		fb->fb.var.xres = fbwidth;
+		fb->fb.var.yres = fbheight;
+		fb->fb.var.xres_virtual = fbwidth;
+		fb->fb.var.yres_virtual = fbheight;
+		fb->fb.var.bits_per_pixel = fbdepth;
+	}
+
 	fb->fb.var.vmode = FB_VMODE_NONINTERLACED;
 	fb->fb.var.activate = FB_ACTIVATE_NOW;
 	fb->fb.var.nonstd = 0;
@@ -749,26 +871,23 @@ static int bcm2708_fb_register(struct bc
 	fb->fb.monspecs.dclkmax = 100000000;
 
 	bcm2708_fb_set_bitfields(&fb->fb.var);
-	init_waitqueue_head(&fb->dma_waitq);
 
 	/*
 	 * Allocate colourmap.
 	 */
-
 	fb_set_var(&fb->fb, &fb->fb.var);
+
 	ret = bcm2708_fb_set_par(&fb->fb);
+
 	if (ret)
 		return ret;
 
-	print_debug("BCM2708FB: registering framebuffer (%dx%d@%d) (%d)\n",
-		    fbwidth, fbheight, fbdepth, fbswap);
-
 	ret = register_framebuffer(&fb->fb);
-	print_debug("BCM2708FB: register framebuffer (%d)\n", ret);
+
 	if (ret == 0)
 		goto out;
 
-	print_debug("BCM2708FB: cannot register framebuffer (%d)\n", ret);
+	dev_warn(fb->fb.dev, "Unable to register framebuffer (%d)\n", ret);
 out:
 	return ret;
 }
@@ -777,10 +896,18 @@ static int bcm2708_fb_probe(struct platf
 {
 	struct device_node *fw_np;
 	struct rpi_firmware *fw;
-	struct bcm2708_fb *fb;
-	int ret;
+	int ret, i;
+	u32 num_displays;
+	struct bcm2708_fb_dev *fbdev;
+	struct { u32 base, length; } gpu_mem;
+
+	fbdev = devm_kzalloc(&dev->dev, sizeof(*fbdev), GFP_KERNEL);
+
+	if (!fbdev)
+		return -ENOMEM;
 
 	fw_np = of_parse_phandle(dev->dev.of_node, "firmware", 0);
+
 /* Remove comment when booting without Device Tree is no longer supported
  *	if (!fw_np) {
  *		dev_err(&dev->dev, "Missing firmware node\n");
@@ -788,90 +915,154 @@ static int bcm2708_fb_probe(struct platf
  *	}
  */
 	fw = rpi_firmware_get(fw_np);
+	fbdev->fw = fw;
+
 	if (!fw)
 		return -EPROBE_DEFER;
 
-	fb = kzalloc(sizeof(*fb), GFP_KERNEL);
-	if (!fb) {
-		ret = -ENOMEM;
-		goto free_region;
+	ret = rpi_firmware_property(fw,
+				    RPI_FIRMWARE_FRAMEBUFFER_GET_NUM_DISPLAYS,
+				    &num_displays, sizeof(u32));
+
+	/* If we fail to get the number of displays, or it returns 0, then
+	 * assume old firmware that doesn't have the mailbox call, so just
+	 * set one display
+	 */
+	if (ret || num_displays == 0) {
+		num_displays = 1;
+		dev_err(&dev->dev,
+			"Unable to determine number of FB's. Assuming 1\n");
+		ret = 0;
+	} else {
+		fbdev->firmware_supports_multifb = 1;
+	}
+
+	if (num_displays > MAX_FRAMEBUFFERS) {
+		dev_warn(&dev->dev,
+			 "More displays reported from firmware than supported in driver (%u vs %u)",
+			 num_displays, MAX_FRAMEBUFFERS);
+		num_displays = MAX_FRAMEBUFFERS;
 	}
 
-	fb->fw = fw;
-	bcm2708_fb_debugfs_init(fb);
+	dev_info(&dev->dev, "FB found %d display(s)\n", num_displays);
+
+	/* Set up the DMA information. Note we have just one set of DMA
+	 * parameters to work with all the FB's so requires synchronising when
+	 * being used
+	 */
+
+	mutex_init(&fbdev->dma_mutex);
 
-	fb->cb_base = dma_alloc_wc(&dev->dev, SZ_64K,
-					     &fb->cb_handle, GFP_KERNEL);
-	if (!fb->cb_base) {
+	fbdev->cb_base = dma_alloc_wc(&dev->dev, SZ_64K,
+						&fbdev->cb_handle,
+						GFP_KERNEL);
+	if (!fbdev->cb_base) {
 		dev_err(&dev->dev, "cannot allocate DMA CBs\n");
 		ret = -ENOMEM;
 		goto free_fb;
 	}
 
-	pr_info("BCM2708FB: allocated DMA memory %pad\n", &fb->cb_handle);
-
 	ret = bcm_dma_chan_alloc(BCM_DMA_FEATURE_BULK,
-				 &fb->dma_chan_base, &fb->dma_irq);
+				 &fbdev->dma_chan_base,
+				 &fbdev->dma_irq);
 	if (ret < 0) {
-		dev_err(&dev->dev, "couldn't allocate a DMA channel\n");
+		dev_err(&dev->dev, "Couldn't allocate a DMA channel\n");
 		goto free_cb;
 	}
-	fb->dma_chan = ret;
+	fbdev->dma_chan = ret;
 
-	ret = request_irq(fb->dma_irq, bcm2708_fb_dma_irq,
-			  0, "bcm2708_fb dma", fb);
+	ret = request_irq(fbdev->dma_irq, bcm2708_fb_dma_irq,
+			  0, "bcm2708_fb DMA", fbdev);
 	if (ret) {
-		pr_err("%s: failed to request DMA irq\n", __func__);
+		dev_err(&dev->dev,
+			"Failed to request DMA irq\n");
 		goto free_dma_chan;
 	}
 
-	pr_info("BCM2708FB: allocated DMA channel %d\n", fb->dma_chan);
+	rpi_firmware_property(fbdev->fw,
+			      RPI_FIRMWARE_GET_VC_MEMORY,
+			      &gpu_mem, sizeof(gpu_mem));
+
+	for (i = 0; i < num_displays; i++) {
+		struct bcm2708_fb *fb = &fbdev->displays[i];
+
+		fb->display_settings.display_num = i;
+		fb->dev = dev;
+		fb->fb.device = &dev->dev;
+		fb->fbdev = fbdev;
+
+		fb->gpu.base = gpu_mem.base;
+		fb->gpu.length = gpu_mem.length;
+
+		if (fbdev->firmware_supports_multifb) {
+			ret = rpi_firmware_property(fw,
+						    RPI_FIRMWARE_FRAMEBUFFER_GET_DISPLAY_SETTINGS,
+						    &fb->display_settings,
+						    GET_DISPLAY_SETTINGS_PAYLOAD_SIZE);
+		} else {
+			memset(&fb->display_settings, 0,
+			       sizeof(fb->display_settings));
+		}
 
-	fb->dev = dev;
-	fb->fb.device = &dev->dev;
+		ret = bcm2708_fb_register(fb);
 
-	/* failure here isn't fatal, but we'll fail in vc_mem_copy if
-	 * fb->gpu is not valid
-	 */
-	rpi_firmware_property(fb->fw, RPI_FIRMWARE_GET_VC_MEMORY, &fb->gpu,
-			      sizeof(fb->gpu));
+		if (ret == 0) {
+			bcm2708_fb_debugfs_init(fb);
 
-	ret = bcm2708_fb_register(fb);
-	if (ret == 0) {
-		platform_set_drvdata(dev, fb);
-		goto out;
+			fbdev->num_displays++;
+
+			dev_info(&dev->dev,
+				 "Registered framebuffer for display %u, size %ux%u\n",
+				 fb->display_settings.display_num,
+				 fb->fb.var.xres,
+				 fb->fb.var.yres);
+		} else {
+			// Use this to flag if this FB entry is in use.
+			fb->fbdev = NULL;
+		}
+	}
+
+	// Did we actually successfully create any FB's?
+	if (fbdev->num_displays) {
+		init_waitqueue_head(&fbdev->dma_waitq);
+		platform_set_drvdata(dev, fbdev);
+		return ret;
 	}
 
 free_dma_chan:
-	bcm_dma_chan_free(fb->dma_chan);
+	bcm_dma_chan_free(fbdev->dma_chan);
 free_cb:
-	dma_free_wc(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
+	dma_free_wc(&dev->dev, SZ_64K, fbdev->cb_base,
+			      fbdev->cb_handle);
 free_fb:
-	kfree(fb);
-free_region:
 	dev_err(&dev->dev, "probe failed, err %d\n", ret);
-out:
+
 	return ret;
 }
 
 static int bcm2708_fb_remove(struct platform_device *dev)
 {
-	struct bcm2708_fb *fb = platform_get_drvdata(dev);
+	struct bcm2708_fb_dev *fbdev = platform_get_drvdata(dev);
+	int i;
 
 	platform_set_drvdata(dev, NULL);
 
-	if (fb->fb.screen_base)
-		iounmap(fb->fb.screen_base);
-	unregister_framebuffer(&fb->fb);
-
-	dma_free_wc(&dev->dev, SZ_64K, fb->cb_base, fb->cb_handle);
-	bcm_dma_chan_free(fb->dma_chan);
-
-	bcm2708_fb_debugfs_deinit(fb);
+	for (i = 0; i < fbdev->num_displays; i++) {
+		if (fbdev->displays[i].fb.screen_base)
+			iounmap(fbdev->displays[i].fb.screen_base);
+
+		if (fbdev->displays[i].fbdev) {
+			unregister_framebuffer(&fbdev->displays[i].fb);
+			bcm2708_fb_debugfs_deinit(&fbdev->displays[i]);
+		}
+	}
 
-	free_irq(fb->dma_irq, fb);
+	dma_free_wc(&dev->dev, SZ_64K, fbdev->cb_base,
+			      fbdev->cb_handle);
+	bcm_dma_chan_free(fbdev->dma_chan);
+	free_irq(fbdev->dma_irq, fbdev);
 
-	kfree(fb);
+	mutex_destroy(&fbdev->dma_mutex);
 
 	return 0;
 }
@@ -886,10 +1077,10 @@ static struct platform_driver bcm2708_fb
 	.probe = bcm2708_fb_probe,
 	.remove = bcm2708_fb_remove,
 	.driver = {
-		   .name = DRIVER_NAME,
-		   .owner = THIS_MODULE,
-		   .of_match_table = bcm2708_fb_of_match_table,
-		   },
+		  .name = DRIVER_NAME,
+		  .owner = THIS_MODULE,
+		  .of_match_table = bcm2708_fb_of_match_table,
+		  },
 };
 
 static int __init bcm2708_fb_init(void)
